Crossing the Gulf of the Farallones is always an eventful experience. Currents and tides aggregate plankton and planktivorous (plankton-eating) fish, which in turn attract harbor porpoises, seabirds and humpback whales. The rich seawater upwelled from the deep waters, feeds a proliferation of plankton, attracting marine life from across the Pacific into the Sanctuary waters. One of the most unusual fish is the giant ocean sunfish.